Can't penetrate the password procedure on the General board so am replying here in the hope it may reach the enquirer.

Canon Stenning in his book The Isle of Man, Robert Hale Ltd., London, 1950 gives the following. The Manx Derby was started around 1630 and was run on a course near Derbyhaven. The Rules and Regulations for the race were put on paper in 1669, and may still be seen.

The race on the Island ended with the Derby period when in 1736 James Stanley the 10th Earl was succeeded by James Duke of Atholl.